Feed dog with replaceable insert



March 31, 1970 I J, SQLOMQN 3,503,351

FEED DOG WITH REPLACEABLE INSERT Filed July 12, 1968 United States Patent 3,503,351 FEED DOG WITH REPLACEABLE INSERT Leonard J. Solomon, 7936 Biscayne Point Circle, Miami Beach, Fla. 33141 Filed July 12, 1968, Ser. No. 744,375 Int. Cl. D05b 27/02 US. Cl. 1l2-216 6 Claims ABSTRACT OF THE DISCLOSURE An improved sewing machine feed dog is disclosed. The feed dog contains a replaceable insert which is pressfit into a bored hole. A thread guide opening is provided in the insert which is formed of a highly wear-resistant material, preferably case-hardened steel or porcelain. When the thread guide opening wears, the insert is replaced, thereby allowing re-use of the feed dog.

This invention relates to sewing machines generally, and more particularly this invention relates to an im proved feed dog for a sewing machine.

Various types of sewing machines are presently being marketed ranging from relatively small portable machines for home use to large heavy-duty machines designed for various commercial purposes. These include, of course, sewing machines used in the manufacture of clothing, sewing machines used to stitch such heavy-weight materials as canvas for tents and the like, and sewing machines used to stitch leather in the making of shoes, hand bags and the like. Those sewing machines designed for light-duty, or home, use usually present minimal problems in the wearing out of parts, but those machines used in various commercial applications have certain parts which require frequent replacement due to wear. One of these parts which wears relatively rapidly is the feed dog of the type which includes a thread guide opening therein.

Conventional feed dogs come in a variety of styles, sizes, and shapes depending on the purpose for which the sewing machine is used. Some are used merely to advance fabric, or other material, through the sewing machine. They have a fabric-contacting member secured thereto and impart the proper movement to the same. Alternatively, some have the feed teeth integral with the feed dog itself. Others have a provision for guiding the thread from the bobbin through the feed dog rather than around it. Such a guide is in the form of an opening, or hole, in the feed dog, whether or not the feed teeth are integral therewith.

In certain applications, such as the manufacture of leather goods, and particularly footwear, a relatively heavy thread is used. Such thread is not only relatively heavy in weight, but it is also rough in texture. In passing through the thread guide opening of the feed dog it gradually causes a wearing away of the opening thereby enlarging the same and making it rough. The result of this extraordinary wear is that the feed dog has to be replaced every three to four days in normal use at a substantial cost in terms of both time and money. Once the thread guide opening is worn, the feed dog is, for all practical purposes, useless although the feed dog itself is in relatively good condition and could be used but for the worn opening.

It is, therefore, a primary object of this invention to provide a feed dog which is free of the aforementioned and other such disadvantages. It is another important object of this invention to provide a re-usable feed dog. More specifically, and consistent with the aforementioned objects, it is an object of this invention to provide a feed dog which includes a replaceable insert which has a thread guide opening therein. Still further, it is an object of this ice invention to provide a feed dog with a replaceable insert formed of a highly wear-resistant material and which has a thread guide opening therein.

Consistent with these and still further objects of this invention, which will become more readily apparent as the description thereof proceeds, the improved feed dog of this invention includes an insert formed of a highly wear-resistant material, with the insert including portions defining a thread guide opening therein. The thread guide opening of a conventional feed dog is enlarged by drilling and the metal insert, or sleeve, is inserted to form a friction fit. The thread guide opening in the insert is at least partially tapered to assist in guiding the thread passing therethrough. The insert is formed of a highly wearresistant material, preferably case-hardened steel or porcelain.

This invention will be better understood, and objects other than those set forth above will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIGURE 1 is an enlarged exploded perspective view of a feed dog according to this invention;

FIGURE 2 is an enlarged fragmental perspective view of the feed dog of FIGURE 1 with the insert in position; and

FIGURE 3 is a cross-sectional view taken on line 33 of FIGURE 2.

In the various figures, like reference characters refer to like parts.

Turning first to FIGURE 1 there can be seen a feed dog generally designated by the numeral 10 with mounting holes 12, feed teeth 13 and a thread guide opening 14 which has been bored out to receive the insert generally designated by the numeral 16. The feed dog 10 depicted herein is of a type conventionally used in sewing machines adapted for use in manufacture of footwear. Accordingly, it will be appreciated that the sewing machine receives considerable use and consequently the feed dog is subjected to a maximum of wear. It should be understood, however, that this invention is equally applicable to feed dogs of other styles used in sewing machines which are adapted for manufacturing other types of articles.

The feed dog insert 16 is formed of a highly wear-resistant material, the preferred materials being case-hardened steel and porcelain. The insert has a peripheral rim 18 at one end thereof which is exaggerated in the drawing. The peripheral rim 18 assists in securing the insert in the enlarged bore 14 of the feed dog 10-. The rim 18, extending outwardly for a greater distance than the remaining portion 20, becomes compressed when the insert is forced into the bore 14 and insures a tight fit. The insert 16 has a bore 22 which tapers inwardly to form sloping wall 24. The bore 14 is of such a dimension that the insert 16 will press-fit into said bore to be carried thereby. When the thread guide opening 22 in the insert 16 wears to a degree that it is no longer usable, the insert 16 is punched out and replaced, providing a feed dog which is re-usable indefinitely as long as other wear surfaces remain in good condition.

Attention is directed to FIGURE 2 where it can be seen that the insert 16 is press-fit into the bore 14 such that the peripheral surface 26 is flush with surface 28 of feed dog 10. In the cross-sectional view of FIGURE 3, the press-fit of the insert 16 into the bore 14 is clearly shown with the flush surfaces 26 and 28 also evident. The thread guide opening 22 includes the tapered wall 24 extending part of the distance therethrough, the remainder being essentially straight as depicted by the numeral 30 It should be apparent from the foregoing detailed description that the objects set forth at the outset to the specification have been successfully achieved. Moreover; while there is shown anddescribed a present preferred embodiment of the invention, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope thereof.

Accordingly, what is claimed is:

1. In a sewing machine feed dog, the improvement which comprises an insert formed of a highly Wear-resistant material, said insert being replaceably carried by said feed dog and including portions defining a thread guide opening therein. i

2. The improvement of claim 1 wherein said feed dog includes portions defining an enlarged bore, said insert being press-fit into said bore.

3. The improvement of claim 2 wherein said insert has a peripheral rim surrounding one end of the same, said rim serving to assist in securing said insert in said bore.

4. The improvement of claim 1 wherein said thread guide openingv is tapered.

5. The improvement of claim 1 wherein said insert is formed of case-hardened steel.

6. The improvement of claim 1 wherein said insert is formed of porcelain.

References Cited UNITED STATES PATENTS 1,263,088 4/1918 McNeil l12216 5 RICHARD J. SCANLAN, In, Primary Examiner 

